Explanation

(d)
Given that $x^{2} - 3x + 2$ be a factor of $x^{4} - px^{2} + q = 0$ ...(i)
$\Rightarrow \left( x^{2} - 3x + 2 \right) = 0$
$\Rightarrow (x - 2)(x - 1) = 0$
$\Rightarrow x = 2,\ 1$
On putting these values in Eq. (i), we get
$4p - q - 16 = 0$ ...(ii)
and $p - q - 1 = 0$ ...(iii)
On solving Eqs.(ii) and (iii), we get
$p = 5\ and\ q = 4$
$\Rightarrow (p,q) = (5,4)$